Leaching characteristics of the heavy metals in spent vanadium and titanium SCR catalyst

doi:10.16085/j.issn.1000-6613.2017-2269

Abstract

Abstract: To study leaching toxicity and leaching characteristics of the heavy metals in spent SCR catalysts, we collected spent SCR catalysts from a certain power plant in Shandong. The leaching toxicity experiment for spent SCR catalyst was carried out by using the sulfuric acid/nitric acid method (HJ/T299-2007), and the leaching characteristics of heavy metals in spent SCR catalyst were studied at different pH, different leaching time and different liquid-solid ratios. The results show that the spent SCR catalysts have certain leaching toxicity, and the leaching concentration of V and Zn are high, which are 13.8mg/L and 2.1mg/L, respectively. pH has a great effect on the leaching of heavy metals. The leaching of Cr, Ni, Cu and Zn is promoted by strong acid, and V is easy to release under strong acid and alkali environment(pH<3 or pH>11). V, Cr, Ni and Cu were mainly released within 2h. Their release rates were higher than 96% at 18h, and the leaching of the four heavy metals were nearly completed after 18h. 6% of the Zn was still released after 18h, and the leaching cycle is relatively long. At room temperature, increasing the liquid-solid ratio only exerts a dilution effect on the leaching of V, while the dissolution of Cr, Ni, Cu and Zn are limited by the solubility at L/S<30, and they will be diluted when L/S>30.

Key words: selective catalytic reduction, catalyst, waste treatment, heavy metals, leaching, toxicity

摘要： 为探讨废弃选择性催化还原（SCR）催钒钛系催化剂中重金属的浸出毒性及其浸出特性，收集了山东某电厂的废弃SCR催化剂进行实验。采用固体废弃物毒性浸出方法硫酸/硝酸法（HJ/T299-2007）进行废弃SCR催化剂毒性浸出实验，同时开展了不同溶液pH、不同浸出时间和不同液固比（L/S）下废弃SCR催化剂中重金属浸出特性的实验研究。结果表明：废弃钒钛系SCR催化剂有一定的重金属浸出毒性，其中V和Zn的浸出浓度偏高，分别为13.8mg/L和2.1mg/L；pH对重金属的浸出影响显著，强酸对Cr、Ni、Cu和Zn的浸出有促进作用，V在强酸强碱环境下（pH<3或pH>11）容易释放；V、Cr、Ni和Cu主要在浸出过程的前2h内释放，18h时释放率都已高达96%以上，18h后这4种重金属浸出基本完成，而Zn在浸出18h后仍有6%释放，浸出周期相对较长；室温下加大液固比对废弃催化剂中V的浸出仅起稀释作用；Cr、Ni、Cu和Zn的溶出在液固比（L/S）<30时受溶解度的影响，L/S>30时被稀释。

关键词: 选择催化还原, 催化剂, 废物处理, 重金属, 浸取, 毒性

CLC Number:

DAI Zejun, WANG Lele, TANG Hao, SU Sheng, YANG Tao, LIU Wei, XU Kai, WANG Yi, HU Song, XIANG Jun. Leaching characteristics of the heavy metals in spent vanadium and titanium SCR catalyst[J]. Chemical Industry and Engineering Progress, 2018, 37(10): 3873-3878.

戴泽军, 王乐乐, 唐浩, 苏胜, 杨涛, 刘威, 许凯, 汪一, 胡松, 向军. 废弃钒钛系选择性催化还原催化剂重金属浸出特性[J]. 化工进展, 2018, 37(10): 3873-3878.

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